SOLUTION: a father and his son can clean the house together in 6 hours. When the son works alone, it take him an hour longer to clean than it takes his dad alone. find how long it takes the
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Question 766364: a father and his son can clean the house together in 6 hours. When the son works alone, it take him an hour longer to clean than it takes his dad alone. find how long it takes the son to clean alone. Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website! a father and his son can clean the house together in 6 hours. When the son works alone, it take him an hour longer to clean than it takes his dad alone. find how long it takes the son to clean alone.
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Together:: time = 6 hr/job::: rate = 1/6 job/hr
Dad::::::: time = x hr/job::: rate = 1/x job/hr
Son::::::: time = x+1 hr/job: rate = 1/(x+1) job/hr
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Equation:
rate + rate = together rate
1/x + 1/(x+1) = 1/6
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6(x+1) + 6x = x(x+1)
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12x + 6 = x^2 + x
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x^2 -11x - 6 = 0
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x = [11 +- sqrt(121-4*-6)]/2
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x = [11+- sqrt(145)]/2
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Positive solution::
x = 11.5 hrs (son's time)
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Cheers,
Stan H.
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